Fast-mode kinetics in surface-mediated phase-separating fluids

We present time-resolved elastic light scattering results of structure determination in phase-separating mixtures of guaiacol and glycerol-water constrained to lie between plates 0.5 mm apart. The structure functions show two peaks with different kinetics: a slow mode with L(t){~}t1/3 and a ``fast mode'' with L(t){~}tᵇ, where b ranges from 1.1 for a quench of depth {Δ}T=0.01^∘{}C to 1.5 when {Δ}T{≥}0.15^∘{}C. A similar fast mode was observed in a polymer system [A. Cumming, P. Wiltzius, F. S. Bates, and J.H. Rosedale, Phys. Rev. A 45, 885 (1992)]. The observation of the fast mode in a low-molecular-weight, Ising-like system establishes it as generic to phase-separating fluids, and not peculiar to polymers.